The present invention generally relates to subscriber set-top boxes (STB) and more particularly concerns subscriber STB's capable of receiving and processing both analog and digital television signals.
Analog STB's (i.e. STB's capable of receiving and processing analog television signals) have been in use in cable systems for many years. Great strides have recently been made in new technology for transmitting and receiving digital television signals. For example, high speed modems employing digital VSB technology have been demonstrated for both terrestial and cable use and IC's are now available for compressing and packetizing video signals according to the MPEG standard. Digital audio compression IC's are also available using, for example, Dolby technology. Complementary IC's for decompressing and depacketizing the received signal are likewise now available.
Using this new digital technology, it is possible to transmit a number of video programs (e.g. 2-10 based on content) or other digital data on a single 6 MHz cable television channel. While cable operators and other information providers are very interested in the expanded data capacity that this technology provides, this interest has been somewhat tempered by the relative unavailability of programming in the digital format relative to that available in analog form, the relatively high cost of the digital technology and compatibility concerns with the large base of installed analog STB's. A proposed solution to the programming availability and compatibility issues is the use of a hybrid STB capable of receiving and processing both analog and digital television signals. The high cost of the digital technology, however, still remains a problem, as does the matter of efficiently integrating the analog and digital processing functions in the hybrid STB. It is therefore a basic object of the present invention to provide an improved architecture for a hybrid analog/digital STB and, in particular, an improved architecture which allows for efficient yet flexible integration of the analog and digital processing functions of the STB which facilitate cost reductions in the manufacture thereof.